im looking at getting BMR's Strut tower brace, im just curious if its worth it the get the 3 point or to just use the 2 point.

ive heard some people having issues of the force pushing onto the middle third point, and forcing to much onto the mount point and causing issues?

any input would be great

 

how is your suspension? if your struts are bad its not gonna do much more than look cool

 

As far as I've been able to learn, after some searching recently, there is no issue with cowl mounted STBs--all seems to be rumor and/or hearsay. If there were issues, the net and this board would be brimming with complaints, but there are none. That said, the STB is pretty much eye candy unless you use a spherical strut mount.

https://www.thirdgen.org/forums/susp...wer-brace.html

JamesC

 

the 3 pt should be much stronger/add more strength. again, assuming good spherical strut mounts.

 

i have decent struts, there not even a year old, cant rememeber who thir from tho, (eibach springs tho)
so if i dont have spherical mounts it wont matter? what exactly is the difference?

 

Since the OE mounts contain rubber, which deflect, they defeat the purpose of the STB, which is to reduce flex. No deflection with the spherical mounts.

JamesC

 

STB eliminate chassis flex, and it does that.

 

They work towards eliminating....but I would not say they "eliminate". A better choice of words would be "reduce"

 

well of course you can never complete eliminate flex. Thats the point tho, it has nothing to do with the strut mounts, or struts. Its like a wonderbar it connects to the strut towers, and it looks badass I have the BMR 3point STB, SBC, and chrome-molly wonderbar. I cant tell what helped the most cuz I did them all at the same time but its way stiffer now

 

a 3-point STB is very effective in greatly reducing flex
and shake of the front end structure of a thirdgen-
without a 3pt STB or other reinforcement, the front clip
of a third will "matchbox"to a clearly visable degree-
just drive one with the hood off over rough ground and
watch the radiator support move and jiggle independant
of the cowl area
If you want a rigid third,3pt STB or other reinforcement
is as important as a good set of SFCs

 

SOLD lol

ive got almost everything picked out from BMR , just deciding if i should get trailing arms or not

 

I've had an Edelbrock 3-pt & swapped it out for a UMI 2-pt. I notice ZERO reduction on stiffness. The UMI piece was WAY easier to install & requires no holes to be drilled. Unfortunately, I still have empty holes from the Edelbrock STB install.

I haven't looked at the BMR piece, but I highly recommend the UMI 2-pt. Just won't work with a carb or TBI.

 

hmm ill have to contemplate it

i all abut brand loyalty so once i pick something thats it! (CHEVY) lol!

 

This from the link I posted above (vetruck):

You may think my question is off topic, but it is not. How good are your strut mounts and what type do you have?
You need good solid aftermarket strut mount first before you will aid in any perfomance gain from a STB. Good solid strut mounts are a far better bang for the buck in performance handling. Without them, the STB is basicallly useless.
Dean


JamesC

 

I dont have aftermarket strut mounts but all I'm saying is they are two different mods one you stiffining up the chassis the other is suspension work, its just two completely different things. The only way your gonna really notice most handling mods anyway is by taking it to a course and doing before and after laps.

 

That must work in conjunction for the best handling.

JamesC

 

I agree and in order for the suspension to work the way its designed it must have as little chassis flex as possible, and this is with any car.

 

My friend, you are way off track. How can I politely tell you you are as wrong as the other end of the spectrum.

What other reason would you have for bracing this area of the car? so it doesn;t fall apart? To simply add extra weight for no reason? For looks?...No,no, and no. It is simply to brace the towers from moving and changing the strut mount relations towards eachother, moving off the lower suspension pickup points laterally, AND the rear wheels (Yes, I said AND THE REAR WHEELS)

99% of you will never even to begin to feel rear wheel flex problems with your strut towers flexing towards the windshield diagonally. Thats why not alot of you think this is necessary for a 3pt setup. I pull it off my car and you would see a major difference in the inside rear wheel locking up going into a hard braking corner. YOU DEFINATELY can tell if I remove the 3rd points and left jus tthe 2pt stb. WHy most of you do not noticed this? Your cars are too heavy, yopur chasis bracing is inadequate in various places, most of you have other weak lins that fail first before this is ever felt, and you do not have the braking capacity and sweet spot feel my car had the the massive brake setup. I had so much brake pedal control it is indescribable to anyone only driving on 1le type brakes in there 3rd gen...night and day difference in chassis feel.

There was a video flaoting around of me in my car at an autox event where alot of us locals had a grudge match. In that vidseo, you can see the last few corners near the finish line where I am close enough to the camera man to see the car just sweetly set and difrt very mldly and roll understeer the rear axle right back out of the corners. You can just see the car bbeing set intot he corner with my pedals (both brake and gas) When a car is done right, you become one with the chassis- there is no fight in the wheel, there is relaxation and modulation time to controi things 'sweetly". The only fight I had in this car was staying in the driver seat- that was until I had to finally put the Momo race seats into it to keep my **** in position and my sides bolstered for the cornering forces this think made. It was a struggle in 60 seconds of corner after corner to stay in that stock factory seat.

Their comes a level where the 3rd pt mount bracing towards the windshield IS needed. Its a mater of whether you ever reach that level or not...AND the matter of if there are some other weak ppoints of the car that will fail first before this is reached.

A guy reaching .94 later g's and saying this to a guy reaching .98 lateral g's and saying thigs don't flex is like this guyy telling the other guy he hiot the wall with his front bumper at 5mph and no damage, so you can now safely do it a 8mph with no damage...wrong

 

so whats the point of all this? your basically saying what I'm saying. That the STB eliminates chassis flex. Take a look at BMR's page it tells you what its desigened to do.
http://www.bmrfabrication.com/F3-chassis.htm

 

Every part compliments another. STB to Strut mounts to Shocks to Tires. Ve knows his stuff. It'd be like buying nice shocks but keeping the sagging springs. Get the mounts and the STB and be good to go. J&M mounts are only $220 now. The mounts will be 100% better of an upgrade by them self than the STB by itself. Do the mounts and STB together or at least do the mounts first...please.

www.hotpart.com for the mounts, or www.spohn.net for theirs. I'd choose J&M/Hotpart since they have adjustable caster/camber.

 

First of all, you need to drop your habit of using the word "eliminate"

They do not eliminate chasis flex, they reduce chasis flex. You start boasting false imformation and you will upset people. A manufacturer that boasts this produc tto eliminate flex would be lying. Please learn to use the proper terms. Can you eliminate through reduction? Yes but also no! Depends on the application and stress applied. An 8" square block of Titanium can bend...get my point? If the planet Mars landed on it, but its IS possible.

---------------------------------
Secondly, You made the statement-
Quote: ...its just two completely different things.

--------------------------------------

It is not. A will help B, but B will not help A unless A is replace to a solid bushing.

My point? You can put a STB on all day long and it is useless until you put a solid sturt mount onto the car. A is a stand alone product where as B is not.

The level you need to acheiev in perforemance to get to the point where the 3rd pt on the STB plas a part of rear chassis aid is not going to come close to play until the struts mounts go solid to maintain caster as well as camber specs- Caster angle and strut shaft length has adjustment affect on the rear of the car jacking under braking along with cg,brake bias, rear springrate/shock dampering, and Tq arm length. It is in essence like an anti dive related product on a front double a-arm car.

 

o okay that makes sense, so what your saying is with stock strut mounts the car wont be pushed hard enough to the feel the useful affects of the STB. I'm not trying to argue BTW I'm just trying to understand it, and when I say eliminate of course I mean reduce, you can never completely eliminate chassis flex

 

I think I'm gonna pick some of solid mount caster camber plates

 

Replacing the stock strut mounts isnt necessary to feel a noticeable difference in handeling if you have a 3 point brace. But I'm not saying they wouldnt help either, I agree with JamesC, but only as far as to say the solid mounts would be better. Allow me to explain in detail:

I recently installed TDS inner framerail sub frame connectors, and BMR outer frame rail connectors, a UMI torque arm relocator, and the BMR wonder bar. I felt a noticeable difference when tearing down a favorite twisty road.

My windows ratteled against the roof of the car over bumpy roads before the chassis upgrades and still did after all that stuff I named off, but I "think" it wasnt as severe. I mention this as an indicator to how much body flex there was under normal driving conditions.

Then I went back a few days later and did the BMR 3 point STB. It made a huge difference and the window rattles were completly gone for about a month, they returned but only slightly. Go figure. Based solely on the window rattels, the 3 point STB reduced body flex more than the wonder bar, and both sets of SFC's combined.

I have a favorite handeling road near my home where I tear through the turns and occasionally drift out into the other lane when I take them too fast. I'm not saying this to brag, I'm saying this to let you know that I am actually out there and on the throttle testing this stuff. Before the car had a lot of understeer. The SFC's and wonderbar didint do much to remedy that. The 3 point STB did a lot though. The car still has understeer mind you, but much much less. Overall I think the 3 point brace helped almost as much as both SFC's and the wonder bar combined.

The STB did these improvements with the stock strut mounts. Unfortunatly I did not test an exact MPH that my car could take this turn at before and after. But on this twisty road I like so much, I used to take it somewhere in the mid 60's with some drift if I got closer to 70mph.(Its a 2 lane in each direction road) With the SFC, wonderbar and torque arm I was taking it at just under 70mph with very little drift. After the STB I am taking this turn at just over 70mph with little drift. At around 75mph, it will drift into the other lane though.

I cant say if a 2 point would have done as much since I've never had one but I was very pleased with the 3 point. Maybe one day when I'm bored I will disconnect the 3rd point and go take that turn :P

 

Thanks for your real world report on your chassis upgrades, always wondered if it was really worth it to have a STB installed and now I know

 

 

the 3rd pt braces of the STB will make a car understeer more, not oversteer as you discribe. Taking them off will loosen the rear of the car and make it rotate into a corner easier because the chjassis flexes up in the inside rear where as the 3rd pts make the inside rear of the car stay more planted and understeer.

Your conclusions do not add up properly, you have something else going on. Yes the STB 3rd pts will help with rattles, maybe that alone give you the better feel of going faster and smoother, BUT, I will tell you fist hand they make the car push, not rotate

 

The stiffer the body, the better....I use a 3 pit STB by Edlbrock which really stiffens the front end....the more attachment points the better....even for just plain bumpy roads....my 84 TA had no braces of any kind, and on bumpy roads ( like my street) the steering wheel would be going one way and the body the other. Having restored an 84, then an 87 i noticed that GM added a few small diameter braces along the way, from the frame rails up to the strut towers. .and the one under the radiator support. I guess the GM engineers' thought they were needed....so the more attachment points the better....even for a daily driver!

 

generaly that is what one feels when adding braces. Its not really the point that its helping the tire footprint, its helping take away unwanted steering inputs and giving overall more predictable sddrive controls that makes the driver feel the car is faster and easier to handle. You can actually go lower in grip coefficiant but increase lateral speed through simple comfort.

How is that possible? less grip but more lateral speed? Simple.
The more the tires grip but the chassis is unstable, the more the driver works the control yaw imputs into the car and the grip rating being higher and unpredictable can cause the car to spin when one corner of the car exceeds the other in grip thus yaw....so, lees grip can often give a driver more predictable control.

 

I don't put much stock in the "real world" impressions that people post.

The human mind is so easily influenced that it is almost pointless to base your conclusions on that single data point. That is why in any experiment where subjective interpretations can influence data, double blind test methods are employed.

Why else do you think that the vast majority of people who install parts instantly "feel" the difference? Why wouldn't you? You just paid a pile of cash for something you are excited to have - it quite simply MUST do something!


This is why some impressions (like Dark Ember's above) don't add up as Dean has pointed out.

Nevermind the fact that in a driving scenario, there are a mountain of factors involved in what ultimately reaches what your hands, feet, and inner ear.

The ONLY way to conclusively PROVE that chassis bracing is doing anything stiffening is to actually measure chassis flex. There are relatively standardized ways of doing this, and I'm surprised that NONE of the chassis component suppliers have taken the time to at least build a fixture to measure torsional rigidity. I could probably build one in my garage if I had a financial incentive to do so.
Then you could actually design things that have at least SOME r&d put into them. This is why I laugh when I see that some of these aftermarket guys claim they put in R&D yet have no real data whatsoever to back up their claims.

In the case of the STB, the stb is probably not going to do very much until the bushings in the strut mounts reach full deflection. I'm guessing that the bushings have a much lower modulus of elasticity than the structure of the car supporting those bushings.

The whole point of all this is to keep as much of the tire on the ground at all times. Id rather take a car with a flexy chassis that kept 100% tread contact and loading at all times than a super stiff chassis that didn't. The flexy car in this case would be much faster. Case in point: racing go karts. Their chassis flex IS their suspension.

I'm just sick of people just believing something is better (in the absence of numbers) like believing in the tooth fairy or Santa Claus

 

For your average 3rd gen owner think were looking more for getting rid of squeaks and rattles then getting that extra .01g in the corner, if a strut brace can pull that off, great.

 

If you want to fix that problem I think you'd be further ahead doing something about the horrible interiors they put in these cars. Upholstered card board, injection molded plastic, plastic screws, plastic threads, nothing applied to plastic on plastic mating surfaces. You're gonna have squeaks and rattles with that kind of build and design quality. Not to mention that the plastics have all been outgassing whatever plasticizers were in them for the past 20 years making the plastic hard and thus more likely to squeak and/or improper interior maintenance, broken mounting clips etc.

Just my

 

The car still has understeer, or, pushes/plows. I just felt like it was not as severe. I would think that a strut tower brace would do more to make the front suspension stiffer than the rear. Maybe thats what diluted what I "thought" I felt. What you said does make some sense though, but I think you meant the outer tire on the turn. The inner tires dont have as much inertia/weight on them afterall. Also, I would add that most of your turns are not a "steady state corner". Thats to say that they arent symmetrical. So depending on if the corner starts easy and then gets sharper, it could change an understeer condition to one of oversteer.

All that technical stuff aside, here is what I am going to do. I am going to go ahead and remove the STB. Then I am going to go find a sharp, 90 degree turn thats as close to a steady state curve as possible. I am then going to go take this turn over and over again in 1 mph increments until I find the mph at which point the car begins to drift out of its curved path through the corner. Then after the tires have had time to cool, I will do it again, just to be sure. Then I will install the STB with and without the 3rd point, and do the same thing. I will find out the exact mph at which the car drifts out and whether its the front or rear that gives first. Although I am pretty sure in this car, its going to be the front drifting out in all 3 cases. Because of that I will also compare a 2nd, wider variable state corner that I think may trigger oversteer in this car. I will also record this as well and post the vids up online. If the car understeers in all cases, then I wont have proved anything about understeer vs oversteer with reguards to how much a 3 point STB helps. But at least I will have some fun abusing the firebird, I know my Monte SS is going to be happy that I'm abusing my wifes firebird for once instead of it. . I will also have doccumented evidence of how many mph you can expect to gain from a STB through a corner. And ultimately thats what this topic was about. I swear, the tangents we get onto in topics never ceases to amaze me lol.